Main results
- (potential) settler mortality/settlements \(\Rightarrow\) early institutions \(\Rightarrow\) current institutions
PSCI 2270 - Week 10
Department of Political Science, Vanderbilt University
November 7, 2023
Project Updates
What if we cannopt randomize?
Instrumental Variables: Colonial origins
Regression Discontinuity: Finding close elections
Differences-in-differences: Tabloid meida in UK
Key idea: Randomization of the treatment makes the treatment and control groups “identical” on average
The two groups are expected to be similar in terms of all characteristics (both observed and unobserved)
If we want to study effects of factor \(X\) on \(Y\) we would ideally want to run an experiment
Uses observational data, but is better than correlation
What is the difference between random and as-if random?
Theories on cholera have two hypotheses of transmission: water or air
As-if random event:
| Water Supply Company | Number of Houses | Deaths From Cholera | Cholera Deaths per 10,000 Houses |
|---|---|---|---|
| Southwark and Vauxhall | 40,046 | 1,263 | 315 |
| Lambeth | 26,107 | 98 | 37 |
| Rest of London | 256,423 | 1,422 | 59 |
Was the exposure actually random?
Random: Lotteries related to politically relevant processes; Timing of events
As-if random: Borders and historical events
Summary:
Question: Why are some countries rich and some are poor? (\(Y\))
Hypothesis: Extractive institutions (\(X\)) are persistent and can affect long-term development
Searching for as-if random assignment:
What is an instrument: Some factor that affects our main independent variable (early institutions) but is unlikely to affect our main outcome (current development) directly
Instrument in Acemoglu, Johnson, and Robinson (2001):
Instead of simple correlation we use two-stage procedure (2SLS)
To prove that instrument is valid researcher needs:
Different sources of data (some predicted mortality, some direct measures) \(\Rightarrow\) Selection bias
Data on troops (some in barracks and some on campaign) \(\Rightarrow\) Selection bias
Why use data on troops at all if it is not the same as settlers \(\Rightarrow\) Measurement validity
Can settlers affect current levels of development not through institutions? \(\Rightarrow\) Violation of excludability